Lighting Design Glossary

Lambertian Surface
Lamberts Cosine Law
Matte

(Term of radiometry/photometry)

A lambertian surface is a surface of
perfectly matte properties, which means that it
adheres to Lamberts cosine law.

Lamberts cosine law states that
the reflected or transmitted luminous intensity in
any direction from an
element of a perfectly diffusing surface varies as the
cosine of the angle between that direction and
the normal vector of the surface. As a consequence,
the luminance of that surface is the same regardless
of the viewing angle.